From 41f2652d8677bbe97cd1fe7792415228f1032bb7 Mon Sep 17 00:00:00 2001
From: bourne-3 <595962708@qq.com>
Date: Tue, 7 Sep 2021 12:13:27 +0800
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---
 .../0129.求根到叶子节点数字之和.md | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/problems/0129.求根到叶子节点数字之和.md b/problems/0129.求根到叶子节点数字之和.md
index 3439cd25..a330991e 100644
--- a/problems/0129.求根到叶子节点数字之和.md
+++ b/problems/0129.求根到叶子节点数字之和.md
@@ -164,6 +164,54 @@ public:
 
 Java： 
 
+```java
+class Solution {
+    List<Integer> path = new ArrayList<>();
+    int res = 0;
+
+    public int sumNumbers(TreeNode root) {
+        // 如果节点为0，那么就返回0
+        if (root == null) return 0;
+        // 首先将根节点放到集合中
+        path.add(root.val);
+        // 开始递归
+        recur(root);
+        return res;
+    }
+
+    public void recur(TreeNode root){
+        if (root.left == null && root.right == null) {
+            // 当是叶子节点的时候，开始处理
+            res += listToInt(path);
+            return;
+        }
+
+        if (root.left != null){
+            // 注意有回溯
+            path.add(root.left.val);
+            recur(root.left);
+            path.remove(path.size() - 1);
+        }
+        if (root.right != null){
+            // 注意有回溯
+            path.add(root.right.val);
+            recur(root.right);
+            path.remove(path.size() - 1);
+        }
+        return;
+    }
+
+    public int listToInt(List<Integer> path){
+        int sum = 0;
+        for (Integer num:path){
+            // sum * 10 表示进位
+            sum = sum * 10 + num;
+        }
+        return sum;
+    }
+}
+```
+
 Python：
 ```python3
 class Solution: